JP2021093383A - Battery pack - Google Patents

Abstract

To provide a battery pack capable of reducing a temperature difference between battery groups.SOLUTION: The battery pack described in the present invention includes: a first battery group in which a plurality of storage batteries having battery-can side surfaces and a battery-can bottom connected to the side surfaces is laminated with their side surfaces facing each other; a second battery group in which a plurality of storage batteries having battery-can side surfaces and a battery-can bottom connected to the side surfaces is laminated with their side surfaces facing each other; and a housing which accommodates the first and second battery groups. The facing surfaces of the first and second battery groups are thermally and directly or in directly connected to each other.SELECTED DRAWING: Figure 2

Description

The present invention relates to a battery pack.

In recent years, the demand for in-vehicle secondary batteries has been increasing against the background of environmental regulations. Among these, lithium-ion secondary batteries are generally considered to be promising because they have a higher discharge potential than lead batteries, nickel-metal hydride batteries, and the like, and therefore can be made smaller and have higher energy densities. For example, further high energy density, high output density, and long life are required for lithium ion secondary batteries for full-scale application. In order to increase the output of the battery, it is effective to increase the potential and input / output a large current from the battery, for example. However, when a large current is input / output from the battery, heat generated due to the internal resistance of the battery is generated inside the battery. If the generated heat cannot be sufficiently removed from the battery, the battery temperature will rise. Battery characteristics such as battery capacity and internal resistance of a lithium-ion battery tend to deteriorate depending on the battery temperature, and in particular, the higher the battery temperature, the lower the battery characteristics often. Therefore, it is necessary to develop a technology for improving the heat dissipation performance of the battery.

When a plurality of lithium-ion cell cells (hereinafter referred to as cell cells) are combined and used as a battery group (for example, when used as a battery module or a battery pack), the temperature difference between the cell cells in the battery group is reduced. It is desirable to do. This is because when the temperature difference between the cells is large, the difference in deterioration is likely to occur between the cells. Since the characteristics of the battery group tend to be rate-determined by the characteristics of the most deteriorated battery among the cells included in the battery group, it is necessary to design the battery group to avoid the structure in which a specific battery deteriorates.

Therefore, in a battery group formed by combining a plurality of cells, a technique for reducing the temperature difference between the cells has been developed. Specifically, in Patent Document 1, an electric tank containing a cell is formed in a rectangular parallelepiped composed of a narrow short side surface and a wide long side surface, and the electric tank is adjacent to each other between the short side surfaces. A storage battery formed by connecting a plurality of single batteries into a collective battery having a required power capacity is described.

On the other hand, when a large current is input / output from the battery, it is necessary to increase the cross-sectional area of the cable connected to the battery. A metal typified by copper is used as a member used for a cable, but the metal generally has a high thermal conductivity and therefore has a high heat dissipation performance.

Japanese Unexamined Patent Publication No. 2000-164186

In the technique described in Patent Document 1, a plurality of ribs are formed on the long side surface of the battery case of each cell. Then, the cell is cooled by forcibly circulating air or the like between the ribs. In such a configuration, when the cooling efficiency is lowered (for example, when the flow rate of the air forcibly circulated is small or when the input / output current is large and the amount of heat generated by the single battery is large), the battery temperature in the configured battery group is reached. Distribution occurs, and in particular, the battery temperature of the cells arranged near the center of the long side surface of the battery group is high, and there is a risk of deterioration. The present invention has been made in view of the above problems, and an object of the present invention is to provide a battery pack having a small temperature difference between battery groups.

The battery pack described in the present invention includes a first battery group in which a plurality of storage batteries having a battery can bottom surface connected to a battery can side surface and a battery can bottom surface are stacked so that the battery can side surfaces face each other, and a battery can side surface and a battery can. It is provided with a second battery group in which a plurality of storage batteries having a bottom surface of a battery can connected to the side surface are stacked so that the side surfaces of the battery can face each other, and a housing for accommodating the first battery group and the second battery group. The battery group and the second battery group are characterized in that their facing surfaces are directly or indirectly thermally connected to each other.

According to the present invention, it is possible to provide a battery pack in which the temperature difference between the battery groups is reduced.

The figure for demonstrating an example of the specific structure of the battery group in Example 1. FIG. The figure for demonstrating an example of the specific structure of the battery group in Example 2. FIG. The figure for demonstrating an example of the specific structure of the battery group in Example 5. The figure for demonstrating an example of the specific structure of the battery group in Example 6. The figure for demonstrating an example of the specific structure of the battery group in Example 7. The figure for demonstrating an example of the specific structure of the battery group in the comparative example 1. FIG. The figure for demonstrating an example of the specific structure of the battery group in the comparative example 2. FIG. The temperature rise ratio figure which showed the temperature rise from the environmental temperature of each cell temperature of the configuration of Examples 1 and 2 and the conventional configuration by the ratio from the lowest temperature in a battery group. The temperature rise ratio figure which showed the temperature rise from the environmental temperature of each cell temperature of the configuration of Examples 3 and 4 and the conventional configuration by the ratio from the lowest temperature in a battery group. The temperature rise ratio figure which showed the temperature rise from the environmental temperature of each cell temperature of the configuration of Examples 5 and 6 and the conventional configuration by the ratio from the lowest temperature in a battery group. The temperature rise ratio figure which showed the temperature rise from the environmental temperature of each cell temperature of the configuration of Example 7 and the conventional configuration by the ratio from the lowest temperature in a battery group. The view which looked at the battery pack of FIG. 2 from the top. The first modification of FIG. The second modification of FIG. The perspective view of the secondary battery of this invention.

A mode for carrying out the present invention will be described. However, the present embodiment is not limited to the following contents, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

This embodiment will be described in detail. Although a lithium ion secondary battery is used as the secondary battery in the present embodiment, this configuration can be applied to other types of storage batteries. Further, the effect can be obtained regardless of the constituent members of the lithium ion secondary battery. That is, in the present invention, an electrode made of an Al current collecting foil and a positive electrode material having a layered structure is used as the positive electrode, and an electrode made of a Cu current collecting foil and a carbon material is used as the negative electrode, but other configurations may be used. For example, as described in Examples 3 and 4, heat dissipation can be improved even when Al foil is used for the negative electrode. The cooling environment is an example and can be applied when other refrigerants are used. Further, although a square battery is used as the shape of the lithium ion battery in this embodiment, the effect can be obtained by using other shapes such as a laminated type battery and a cylindrical type battery.

When a single battery is used as a battery group, the single batteries are connected in series or in parallel. At this time, in order to ensure safety, a member capable of ensuring insulation between the batteries may be introduced around the cell cells, for example, as shown in Example 7. The shape of the member is free and the material can be freely selected, but it is preferable that the heat transfer member is included. When the cells are connected in series or in parallel, the wiring used is not particularly limited, and examples thereof include a bus bar. Regardless of the type of series or parallel connection, the effect will be exhibited by using the battery arrangement and the external terminal configuration according to the present invention. For example, the effect in the present invention can be obtained even in a battery group in which two battery groups arranged in parallel are arranged in six series. Further, in the battery group, in addition to electrically connecting the cells in series or in parallel, it is preferable to physically restrain the batteries by using a fixing jig. However, the present invention is not limited to the method of restraint. For example, the effect was exhibited whether the two battery groups were lashed using one set of fixing jigs or two sets of lashing jigs.

In the present invention, the battery pack is composed of the first battery group and the second battery group connected by the means described above as a basic configuration. In addition to these, the battery pack further includes a battery control device (for example, for example). A Battery Management System (BMS or the like) or a safety mechanism (for example, a fuse or the like) may be provided, and the effect in the present invention can be obtained even if these are connected to the wiring in the battery group.

The method of contacting the bottom surface of the housing and the battery group is not particularly limited, and the effect of the present invention can be obtained by, for example, bonding with an adhesive or connecting via a fixing device using bolts or nuts. The shape of the housing exemplifies a rectangular parallelepiped in the present embodiment, but the shape is not particularly limited. Further, the effect in the present invention is not limited to the current application condition and the cooling condition to the battery pack.

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. FIG. 1 is an exploded perspective view of the battery pack 100 of the present invention. In the following description, the terms up, down, left, right, front and back shall follow the directions described in the lower left of each drawing.

The battery pack 100 includes a first battery group 10A, a second battery group 10B, and a housing 5 (5a, 5b) that houses the first battery group 10A and the second battery group 10B. The housing 5 includes a case 5a and a lid 5b that closes the case opening. Although the bottom surface 5b is a separate member in the present embodiment, the case 5a may be provided with a bottom surface and an opening may be provided on the top surface, or a lid 5b may be arranged on the top surface side.

FIG. 15 is a diagram showing a storage battery 1 used in the present invention. The storage battery 1 includes a pair of wide surfaces 1a, a pair of narrow surfaces 1b, a bottom surface 1c, and a lid 1d. The lid 1d is provided with a positive electrode external terminal 2a and a negative electrode external terminal 2b.

Returning to FIG. 1 again, the first battery group 10A and the second battery group 10B will be described. The first battery group 10A is a stack of a plurality of (six in this embodiment) of the wide surfaces 1a of the storage battery 1 facing each other. Similar to the first battery group 10A, the second battery group 10B also has a structure in which the wide surfaces of the storage batteries are opposed to each other and laminated.

The storage batteries 1 constituting the first battery group 10A are connected in series with each other by a bus bar 2. Similarly, in the second battery group 10B, the storage batteries 1 are connected in series with each other by the bus bar 2. Further, the storage battery 1 on the bottom surface 5b side of the first battery group 10A and the storage battery 1 on the bottom surface 5b side of the second battery group 10Bno are connected to each other by a bus bar 2. Each of the two battery groups 10A and 10B has an external terminal 3 connected to other electronic components (for example, a junction box) housed in the battery pack 100 arranged on the center side of the upper surface of the battery pack 100. There is. In the present invention, the temperature change of the battery pack 100 was measured by several placement methods (FIGS. 1 to 7).

(Example 1)
First, Example 1 will be described. After laying the first battery group and the second battery group flat as shown in FIG. 1, after thermally connecting them directly, a copper HV cable having a diameter of 95 mm is attached to the tip of the positive electrode external terminal and the negative electrode external terminal. It was attached and a current was applied. The amount of heat generated from the battery at this time was 3 W on average.

As a cooling condition, air having a wind speed of 5 m / sec was applied only to the bottom plate via the housing at the bottom of the battery group. FIG. 1 shows the upper surface of the housing. FIG. 8 shows the results when the battery pack is in a nearly steady state after being given this condition.

(Example 2)
Next, Example 2 will be described. The second embodiment is different from the first embodiment in that the first battery group and the second battery group are laid flat and then interposed through the flat plate-shaped heat conductive member 4.

FIG. 2 shows the structure of this embodiment. In this embodiment, as described above, the heat conductive member 4 is arranged between the first battery group 10A and the second battery group 10B. Two thicknesses of 3 mm and 15 mm were prepared for the heat conductive member, and the temperature rise of the battery pack 100 when each was used was measured. The results are shown in FIG. The cooling conditions and the current application conditions are the same as those in the first embodiment.

(Example 3)
Subsequently, Example 3 will be described. Example 3 is different from Example 1 in that the material of the negative electrode current collector foil is copper foil to aluminum current collector foil.

Since the specific structure of the battery pack 100 has the same arrangement as that in FIG. 1, the description thereof will be omitted. The result of the temperature rise of the battery pack 100 is shown in FIG. The cooling conditions and the current application conditions are the same as those in the first embodiment.

(Example 4)
Subsequently, Example 4 will be described. Example 4 is different from Example 2 in that the material of the negative electrode current collector foil is copper foil to aluminum current collector foil. Since the specific structure of the battery pack 100 has the same arrangement as that in FIG. 2, the description thereof will be omitted. In this embodiment, a member having a thickness of 15 mm is used for the heat conductive member 4. The result of the temperature rise of the battery pack 100 is shown in FIG. The cooling conditions and the current application conditions are the same as those in the first embodiment.

(Example 5)
Subsequently, Example 5 will be described. In the fifth embodiment, as compared with the first embodiment, the narrow side surface of the storage battery forming the battery group by vertically arranging the first battery group 10A and the second battery group 10B as shown in FIG. 3 of the battery pack 100 The difference is that they are in contact with the bottom surface of the housing 5. The result of the temperature rise of the battery pack 100 is shown in FIG. The cooling conditions and the current application conditions are the same as those in the first embodiment.

(Example 6)
Subsequently, Example 6 will be described. In Example 6, as compared with Example 2, the first battery group and the second battery group are arranged vertically as shown in FIG. 4, and the narrow side surface of the storage battery constituting the battery group is the housing of the battery pack 100. The difference is that they are in contact with the bottom surface of 5. Further, in this embodiment, two heat conductive members 4 having a thickness of 3 mm and a thickness of 15 mm are prepared as in the second embodiment, and the measurement results of each are shown in FIG. The cooling conditions and the current application conditions are the same as those in the first embodiment.

(Example 7)
Subsequently, Example 7 will be described. This embodiment is different from Examples 1 to 6, in which the first battery group and the second battery group in which the storage batteries 1 are connected in 6 series are connected in series to each other, and the bottom surface of the storage battery 1 is the housing of the battery pack 100. It has a structure provided so as to be in contact with the bottom surface 5b of the above. Also in this embodiment, the heat conductive member 4 is arranged between the first battery group 10A and the second battery group 10B. An aluminum flat plate having a plate thickness of 15 mm is used for the heat conductive member 4. The result of the temperature rise of the battery pack 100 is shown in FIG. The cooling conditions and the current application conditions are the same as those in the first embodiment.

(Comparative Example 1)
Next, Comparative Example 1 will be described. Comparative Example 1 is different from Examples 1 to 7 in that the battery group is not divided into two and is laminated as a single battery group.

FIG. 6 is a diagram of the battery pack 100 of Comparative Example 1. Twelve batteries 1 are connected in series to form a single battery group, which is arranged so that the wide surface 1a of the cell 1 contacts the bottom surface 5b of the housing 5. The results of the temperature rise of the battery pack 100 are shown in FIGS. 8 and 9. The cooling conditions and the current application conditions are the same as those in the first embodiment.

(Comparative Example 2)
Next, Comparative Example 2 will be described. In Comparative Example 2, unlike Examples 1 to 7, the battery group is not divided into two, but is laminated as a single battery group, and the narrow surface 1b of the cell 1 is the bottom surface 5b of the housing 5. The point of contact is different.

FIG. 7 is a diagram of the battery pack 100 of Comparative Example 2. Twelve batteries are connected in series to form a single battery group, which is arranged so that the narrow surface 1b of the cell 1 contacts the bottom surface 5b of the housing 5. The results of the temperature rise of the battery pack 100 are shown in FIGS. 10 and 11. The cooling conditions and the current application conditions are the same as those in the first embodiment. Hereinafter, the effects of this patent will be described based on the results of Examples and Comparative Examples.

As a result of giving the battery group the conditions shown in this example and the comparative example, when the temperature of the battery group reached a nearly steady state, the battery temperature was higher than the environmental temperature. 8 to 11 are diagrams showing the ratio of the temperature rise of each cell in the battery group to the temperature rise of the cell having the smallest temperature rise with respect to the environmental temperature for each battery. The cell numbers in the figure correspond to the cell numbers described in the figures corresponding to the respective examples and comparative examples. At this time, the description of the two battery groups in the examples is omitted for the sake of simplicity because the temperatures of the single batteries existing in the opposite locations of the battery groups are almost the same. The results of each figure will be described in detail below.

FIG. 8 shows the temperature rise ratio of the configurations of Examples 1 and 2, which is an example in which the present invention is applied to the battery arrangement placed flat as in Comparative Example 1. From the figure, in the comparative example having the conventional configuration, the cell No. It can be seen that the temperature of 7 is the maximum. This is cell No. In the battery around 7, the amount of heat generated by the surrounding batteries is not dissipated, so not only the temperature of the own battery but also the temperature of the surrounding batteries is high, and since there is no temperature difference, it becomes difficult for heat to flow, resulting in This is because the battery temperature is high. On the other hand, the temperature rise of the cell No. 1 cell in contact with the bottom surface of the housing and the cell No. 12 in which the external terminal is present is suppressed because the heat dissipation path exists. From the above results, a difference appeared in the rising temperatures of the cells No. 1 and No. 12 and the cells No. 7, and therefore, in Comparative Example 1, the temperature rising ratio changed significantly even in the same battery group. Therefore, in Comparative Example 1, it can be seen that a difference in temperature between the cells is likely to appear.

On the other hand, FIG. 8 shows an embodiment of the present invention at the same time. In the present invention, since the temperature rise rates between the batteries are compared in all cells existing in the same arrangement, it can be seen that the temperature rise rate can be reduced in all cells as compared with the comparative example. Further, it can be seen that by arranging the heat transfer member between the battery groups as shown in the second embodiment, the effect is further exhibited and the temperature difference between the batteries is alleviated. This means that the heat dissipation path can be effectively secured by arranging the external terminal in the cell No. 6 having the highest temperature. In addition, in Example 2, it can be seen that the heat dissipation path can be secured by introducing the Al plate, so that the temperature difference between the batteries can be effectively reduced.

FIG. 9 shows the temperature rise rate of the configurations of Examples 3 to 4, which is an example in which the present invention is applied to the battery configuration laid flat as in Comparative Example 1. From the figure, it can be seen that even when the negative electrode current collector foil is Al, the temperature difference between the batteries tends to be relaxed as shown in FIG. The thermal behavior that occurred in FIG. 9 is due to the same phenomenon that occurred in FIG.

FIG. 10 shows the configurations of Examples 5 to 6, which are examples in which the present invention is applied to the vertically installed battery configuration as in Comparative Example 2. From the figure, in the comparative example having the conventional configuration, the cell No. It can be seen that the temperature of 6 is the maximum. The temperature rise occurring here is due to the same phenomenon as the behavior shown in Comparative Example 1 shown in FIG.

Further, from the figure, it can be seen that the temperature difference between the batteries is alleviated even when the batteries are installed vertically, as in FIGS. Even when placed vertically instead of horizontally, the temperature near the center of the long side tends to rise. It can be seen that by arranging the external terminal and the external terminal in that portion, the same effect as in FIGS. 8 and 9 was obtained, and the difference in rising temperature could be reduced.

FIG. 11 compares the temperature difference when the present invention is applied with the configuration shown in Example 7 with respect to the battery configuration in which the battery is vertically installed as in Comparative Example 2. From the figure, it can be seen that the temperature difference tends to be alleviated even in the present invention. It can be seen that even in the seventh embodiment, the external terminal can be effectively dissipated to the outside of the battery group by installing the external terminal in the cell No. 6 where the battery temperature is the highest.

The battery pack according to the present invention includes a plurality of storage batteries (1) having a battery can bottom surface (1c) connected to a battery can side surface (1a, 1b) and a battery can side surface (1a, 1b). A storage battery (1) having a first battery group (10A) in which 1b) is laminated so as to face each other, and a battery can bottom surface (1c) connected to a battery can side surface (1a, 1b) and a battery can side surface (1a, 1b). A housing for accommodating a second battery group (10B), a first battery group (10A), and a second battery group (10B) in which a plurality of the battery can side surfaces (1a, 1b) are stacked so as to face each other. The body (5) is provided, and the first battery group (10A) and the second battery group (10B) are characterized in that their facing surfaces are directly or indirectly thermally connected to each other. With such a structure, it is possible to provide a battery pack in which the temperature difference between the battery groups is reduced.

Further, in the present invention, the structure is such that the wide surface (1a) of the two battery groups faces the bottom surface of the housing (5). With such a structure, the cooling area becomes large, and the cooling performance is improved as compared with the case where the narrow surface 1b is brought into contact with the housing 5.

Further, in the battery pack described in the present invention, when the wide surface 1a of the battery 1 is turned down, the external terminal 3 is set to the center side of the battery pack to cool the center side of the battery pack in which heat is less likely to escape. , Can be done via an external terminal. Therefore, it is possible to provide a battery pack in which the heat dissipation is further improved and the temperature difference between the battery groups is reduced.

Further, as shown in FIG. 12, in the battery pack described in the present invention, a first heat transfer member (6) is provided between the first battery group (10A) and the second battery group (10B). Arranged, the heat transfer member (6) is brought into close contact with the first battery group (10A) and the second battery group (10B). With such a structure, it is possible to provide a battery pack in which the heat transfer member further promotes heat diffusion and reduces the temperature difference between the battery groups. Note that FIG. 12 is a view of FIG. 2 as viewed from above.

Further, in the battery pack described in the present invention, as shown in FIG. 13, a second heat transfer member 61 and a third heat transfer member 62 are provided on both sides of the first battery group 10A and the second battery group 10B. It may be arranged. In this case, the first battery group 10A is sandwiched between the heat transfer member 6 and the second heat transfer member 61, and the second battery group 10B is sandwiched between the heat transfer member 6 and the third heat transfer member 10B. , Both sides of the battery groups 10A and 10B also have improved heat dissipation, and it is possible to provide a battery pack in which the temperature difference between the battery groups is further reduced.

Further, the battery pack described in the present invention has a structure in which both the second heat transfer member 61 and the third heat transfer member 62 have a width larger than that of the first heat transfer member 6. With such a structure, the housing 5 and the heat transfer members 61 and 62 can be fastened with screws or the like, and the housing 5 and the heat transfer members 61 and 62 can be brought into close contact with each other more firmly. Therefore, it becomes easier to transmit the heat generated by the battery 1 to the housing 5, and it is possible to provide a battery pack having improved cooling performance.

Further, in the battery pack described in the present invention, as shown in FIG. 14, as another form, the first heat transfer member 6 is thicker than the second heat transfer member 61 and the third heat transfer member 62. It has become. With such a structure, it is possible to provide a battery pack in which heat diffusion is further promoted and cooling performance is improved between two battery groups having the worst heat dissipation. In the present invention, the above-mentioned battery pack of the type in which the wide surface 1a of the battery 1 is in contact with the bottom surface of the housing 5 is used for natural cooling so that cooling air does not flow between the battery groups or between the cells. Very effective in some cases. Therefore, the present invention is very suitable for a structure in which the battery 1 is placed horizontally. Further, the present invention is a group of batteries in which a plurality of storage batteries formed on a rectangular body composed of a wide surface and a narrow surface are laminated with the wide surfaces facing each other, and is the first battery. A battery pack including a group and a second battery group, in which the first battery group and the second battery group are arranged side by side and housed in a housing so that the narrow surfaces of the storage batteries face each other. A first heat transfer member is arranged between the first battery group and the second battery group, and the first heat transfer member is the first battery group and the second battery group. In the storage batteries on the upper surfaces of the first battery group and the second battery group, which are in close contact with each other, the first battery group and the second battery group are located on the center side of the battery pack. Is a battery pack in which an external terminal is provided to connect the battery to an electronic circuit in the housing so that heat can be dissipated through the external terminal. Further, the present invention further relates to a second heat transfer member in the battery pack. The first battery group is sandwiched between the first heat transfer member and the second heat transfer member, and the second battery group is the first. It is sandwiched between the heat transfer member and the third heat transfer member, and the second heat transfer member and the third heat transfer member are characterized in that they are thicker than the first heat transfer member. It is a battery pack, and in the present invention, the first battery group is further sandwiched between the first heat transfer member and the second heat transfer member, and the second battery group is the first. The first heat transfer member is sandwiched between the heat transfer member and the third heat transfer member, and the first heat transfer member is thinner than the second heat transfer member and the third heat transfer member. It is a battery pack.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs are designed without departing from the spirit of the present invention described in the claims. You can make changes. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

1 Single battery 2 Wiring 3 External terminal 4 Bottom of the housing 5 Top of the housing 6, 61, 62 Heat transfer member

Claims (4)

A first battery group in which a plurality of storage batteries having a battery can side surface and a battery can bottom surface connected to the battery can side surface are laminated with the battery can side surfaces facing each other,
A second battery group in which a plurality of storage batteries having a battery can side surface and a battery can bottom surface connected to the battery can side surface are laminated with the battery can side surfaces facing each other,
In a battery pack provided with a housing for accommodating the first battery group and the second battery group,
A battery pack characterized in that the first battery group and the second battery group are thermally connected to each other directly or indirectly on opposite surfaces. In the battery pack according to claim 1,
A first heat transfer member is arranged between the first battery group and the second battery group.
A battery pack characterized in that the heat transfer member is brought into close contact with the first battery group and the second battery group. In the battery pack according to any one of claims 1 or 2.
The battery pack has a second heat transfer member and a third heat transfer member.
The first battery group is sandwiched between the first heat transfer member and the second heat transfer member.
The second battery group is sandwiched between the first heat transfer member and the third heat transfer member.
The battery pack, wherein the second heat transfer member and the third heat transfer member are thicker than the first heat transfer member. In the battery pack according to any one of claims 1 to 3.
The battery pack has a second heat transfer member and a third heat transfer member.
The first battery group is sandwiched between the first heat transfer member and the second heat transfer member.
The second battery group is sandwiched between the first heat transfer member and the third heat transfer member.
The battery pack, wherein the first heat transfer member is thinner than the second heat transfer member and the third heat transfer member.

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